1. Field of the Invention
Analyte sensors (e.g. glucose sensors used in the management of diabetes) and methods and materials for making and using such sensors.
2. Description of Related Art
Analyte sensors such as biosensors include devices that use biological elements to convert a chemical analyte in a matrix into a detectable signal. There are many types of biosensors used for a wide variety of analytes. The most studied type of biosensor is the amperometric glucose sensor, which is crucial to the successful glucose level control for diabetes.
A typical glucose sensor works according to the following chemical reactions:
The glucose oxidase is used to catalyze the reaction between glucose and oxygen to yield gluconic acid and hydrogen peroxide (equation 1). The H2O2 reacts electrochemically as shown in equation 2, and the current can be measured by a potentiostat. These reactions, which occur in a variety of oxidoreductases known in the art, are used in a number of amperometric sensor designs.
As analyte sensor technology matures and new applications for sensor technology are developed, there is a need for methods and materials that facilitate the use of sensors in new technological applications. For example, hospitals increasingly use continuous glucose sensors to monitor patent physiology, for example in ICU environments. In such hospital environments, situations arise where a sensor must be disconnected from, and reconnected to, sensor electronics, for example, when a patient needs to undergo a magnetic resonance imaging (MRI) procedure. Because processors are incompatible with MRI, the sensor electronics need to be disconnected from the sensor until the MRI is completed.
In conventional sensor setups, if a sensor is disconnected from and then reconnected to sensor electronics, there is a significant delay before the sensor becomes stabilized enough to start sensing again. The delay can last from several minutes to a couple of hours, thereby complicating care in clinical settings. In addition, in individuals using analyte sensors in non-hospital settings (e.g. diabetics using glucose sensors to manage their disease), relatively long sensor initialization and/or start-up periods following sensor implantation can be problematical due to both the inconvenience to the user as well as the delayed receipt of information relating to user health. Because many diabetics do not have medical training, they may forgo optimal monitoring and modulation of blood glucose levels due to complexities associated with such management, for example, a two hour start-up period which can be an inconvenience in view of a patient's active daily routine.
For the above-noted reasons, methods and sensor systems that are designed to reduce sensor initialization and/or start-up times in are desirable.